Why does each steep get progressively more bitter?

[riccaicedo]

Sorry for the late post, but no one gave a definite answer.

It's due to caffeine. The more you steep, the more caffeine you extract, same thing happens with temperature.

[AdamMY]

Sorry for the late post, but no one gave a definite answer.

It's due to caffeine. The more you steep, the more caffeine you extract, same thing happens with temperature.

I would doubt this, while the 10 second decaf trick is a myth. I would think the fact that it can get more bitter is the likely hood of higher temps, with slightly longer steeps with leaves that are more open, results in a larger transfer of catechins and other bitter components from the leaves. While yes more caffeine can be released, I don't see a huge deal more caffeine being released on the 5th steep even with boiling water and a longer steep, that is a lot more just full on bitter components of the leaves working their way into the broth.

In fact there is a lot more to tea than caffeine and caffeine does not mean bitter, I have had some rather high caffeine coffee that was not that bitter at all. It really depends on how you brew and how everything works out.

[riccaicedo]

Then how do you explain the low bitterness of houjicha and kukicha (which are low in caffeine) even if brewed at high temps, long brewing time?

Caffeine isn't the only chemical in the world that has a bitter flavor but in tea it's the major one.

Catechins are the main agent for astringency as well, so perhaps high astringency may increase the sense of bitterness?

[Chip]

Proof that caffeine is very bitter:
You can also lookup caffeine in wikipedia, it says it's bitter in the first line.

[AdamMY]

Then how do you explain the low bitterness of houjicha and kukicha (which are low in caffeine) even if brewed at high temps, long brewing time?

Caffeine isn't the only chemical in the world that has a bitter flavor but in tea it's the major one.

Catechins are the main agent for astringency as well, so perhaps high astringency may increase the sense of bitterness?

I've had some pretty bitter Houjicha too. I am just saying unless someone wants to run a chemical analysis on each brew of a tea they drink accompanied by well documented tasting notes, we can not be sure. But at the same time while Sencha can get more bitter into the second and possibly even third steeps. I would guess if it still is getting more and more bitter on the 4th or 5th or even later, than it likely is not the caffeine. Caffeine is rather water soluble, it would be hard for more caffeine to be finding its way out after 3 to 4 minutes of steeping than it did in the first 1-2 minutes.

I am not denying that caffeine could be causing bitterness, but the implication in the original post is that each steep, each and every single steep is getting more and more bitter than the last, and that can not logically be explained by caffeine alone.

[Chip]

Maybe it's not caffeine alone, but according to this link:
elmwoodinn dot com slash about slash caffeine dot html

Which has an experiment from a chemistry professor, says that "In fact, it would take a six-minute infusion to remove 80% of the caffeine".

Hence caffeine still plays a role even after a long steeping time.

Why is gyokuro brewed at lower temperatures? To avoid the caffeine (bitter taste) that extracts more efficiently at high temperature while enjoying the mild sweet taste (L-theanine and other amino acids).

I'm also guessing that if you concentrate any tea (by greatly over steeping) we may perceive it as bitter too, aided by the high astringency of catechins.

[AdamMY]

Maybe it's not caffeine alone, but according to this link:
http://elmwoodinn.com/about/caffeine.html

Which has an experiment from a chemistry professor, says that "In fact, it would take a six-minute infusion to remove 80% of the caffeine".

Hence caffeine still plays a role even after a long steeping time.

Why is gyokuro brewed at lower temperatures? To avoid the caffeine (bitter taste) that extracts more efficiently at high temperature while enjoying the mild sweet taste (L-theanine and other amino acids).

I'm also guessing that if you concentrate any tea (by greatly over steeping) we may perceive it as bitter too, aided by the high astringency of catechins.

I wish you wouldn't post links that support my case. For all of the teas in that chart, there was roughly half the caffeine in the second 3 minute infusion than the first three minute infusion. While that likely does not match up with our brewing procedures it does tell us that more caffeine finds its way out initially than later on. By your reckoning how does half the caffeine result in more bitterness, when caffeine is the only source of bitterness?

[riccaicedo]

Hadn't we already agreed that it wasn't caffeine alone? I've said twice that catechins may also be playing a role.

What I'm pointing out is that there is always more caffeine being extracted, all the way to the end. The guy in the experiment reinfused the leaves with fresh water, of course each time the caffeine content is less.

But when we resteep we don't really take out all of the water of the tea pot, do we? Some of the really concentrated liquid still remains, even if it's a tiny amount.

[riccaicedo]

Plus what the original thread says is that after a while it doesn't get bitter anymore, and the less caffeine content could support that fact.

As Alex Zorach says

Unless I up the temperature or greatly up the steeping time with each progressive steeping (both of which I sometimes do) I find it gets less bitter. I've found this true of all kinds of tea.

Perhaps you brewed the first one too hot?

I have another question: If I brew houjicha (roasted bancha) and bancha at the same high temperature for the same amount of time, which one is more bitter and why?

[riccaicedo]

I did more research today and it definitely seems that caffeine and catechin play a role in the bitterness.

I would post the links but I'm not allowed yet, I should have read the forum rules before

Another interesting thing I found, but which is more complicated to discuss, is that people perceive bitterness in a different way than just because of concentration of certain bitter compounds. Other non bitter compounds can heighten or lower the perceived bitterness.

[Chip]

I did more research today and it definitely seems that caffeine and catechin play a role in the bitterness.

I would post the links but I'm not allowed yet, I should have read the forum rules before

Another interesting thing I found, but which is more complicated to discuss, is that people perceive bitterness in a different way than just because of concentration of certain bitter compounds. Other non bitter compounds can heighten or lower the perceived bitterness.

Please feel free to post the links as it may further this discussion ... and it is not self promoting (which was the actual reason for the rule).

[riccaicedo]

"Bitterness of tea is generally ascribed to the combination of catechins, saponin, caffeine, and amino acids. Depending on molecular weight, catechins can be bitter or astringent, whereas saponins are often described as acrid"
source:http://ajcn.nutrition.org/content/72/6/1424.full
American Journal of Clinical Nutrition

On that same page they also state that "The biology of bitter-taste perception is poorly understood. The long-term challenge has been to explain how so many structurally unrelated compounds can give rise to a uniform bitter taste."

The only thing I didn't like about the article was that they often mixed acrid, bitter and astringent without specifically saying which compound does what.

Caffeine for example, is never said to be astringent in any online source, while catechins are often referred to being astringent. However it appears that astringency increases the perceived bitternes along with other compounds (even if they aren't bitter or astringent).

In this link:http://www.coffeeresearch.org/science/bittermain.htm, there are a lot of reasons that affect the perceived bitterness of coffee. For example, "Coffee bitterness is decreased by the addition of sucrose, sodium chloride, or citric acid. Hydrocolloids, in general, were found to decrease the perception of coffee bitterness (Pangborn, 161)."

In conclusion, AdamMY was right from the beginning, it's way more complicated than just a matter of amounts of specific compounds like catechins or caffeine.

[teasme]

I agree that each re-steeping is less and less likely to be bitter in my personal experience. I'm not much of a chemistry buff but these guys seem to know what they're talking about. It could be any number of the reasons listed above or a combination of a few. The water, steeping temp, time, quality of tea, taste buds, etc. It's interesting to hear that you encounter this type of issue though. Hopefully you find a solution to your problem. Good luck!